A Bayer mask is typically used to allow colour component signals to be derived from any array of CCD or other sensing elements, which do not in themselves discriminate colour. A Bayer mask will typically be used to derive red (R), green (G) and blue (B) signals and comprises a rectangular array of R, G and B filters. Since the human eye is more sensitive to brightness than colour, and since the green signal contributes most to the perception of brightness, G filters predominate in the Bayer mask and are quincunxially sampled.
A Bayer mask decoder is used to convert a Bayer mask signal (which has for each sensing element—or pixel—only one of the three R, G and B signals) to an image signal which has at each pixel an R signal, a G signal and a B signal.
It is well known that cross-colour artefacts can result from simple Bayer mask decoders. Many suggestions have been made for reducing these artefacts. Reference is directed, for example, to GB2426881A which discloses a decoder based on non-adaptive linear filters. This decoder performs well on the quincunxially sampled (usually the green) component but exhibits cross-colour artefacts on the more sparsely sampled other (red and blue) components.